Coal mines had their canaries. When it comes to microplastics in the ocean, Alaska has its seabirds.

A nearly decade-long University of Alaska project to monitor the ecology of puffins, crested auklets, and other seabirds that flock to the storm-tossed Aleutian Islands has produced crucial baseline information about microplastics contamination in marine waters off Alaska.

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Of more than 200 Aleutian birds initially examined, nearly one in five turned out to have some type of organic materials in their stomachs, researchers found.

Further investigation revealed that plastic contamination goes well beyond items in birds' guts.

Nearly all of the birds subsequently examined tested positive for at least one type of phthalate in their muscle tissue, said Veronica Padula, a Ph.D. candidate focusing on plastics contamination. There are many types of phthalates, but Padula tested the birds for the six that are considered high priorities by the United States Environmental Protection Agency.

Phthalates are widely used to make plastics softer, more flexible, or more durable. They are found in flooring, cosmetics, medical devices, and a broad array of other products. Once ingested, phthalates can mimic hormones and interfere with reproductive functions.

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It is not yet clear how the phthalates got into the birds—direct ingestion of plastic, eating other creatures that consumed the debris, or through some other type of exposure.

"This is like a Pandora's Box and it just begs more questions all the time," Padula said at the Alaska Marine Science Symposium, held in January in Anchorage. "What it does say is these anthropogenic compounds are in the environment and that these birds are exposed to them in some way, which is meaningful when you consider the fact that they're endocrine-disrupting compounds."

The seabird-monitoring program, launched in 2009, did not start out as a search for plastics, said Doug Causey, a University of Alaska–Anchorage biology professor and Padula's adviser. Causey has been studying Aleutian seabird populations for decades, hitching nearly annual rides in recent years with the U.S. Fish and Wildlife Service's research vessel Tiglax. He has a permit that allows him to shoot birds for research.

One trend he has tracked is the decline of red-faced cormorants, which used to number more than 70,000 in the westernmost Aleutian islands but are now down to a few hundred.

There are multiple suspected causes for the fall in population of red-faced cormorants and other seabird declines, including climate change and shifts in the marine environment.

The plastics epiphany came in 2013, Causey said. That year, a tufted puffin collected off the remote island of Amchitka was found to have a sharp piece of plastic—possibly from a bottle—lodged inside its body, piercing its stomach wall and scarring its esophagus.

Discovery of the Amchitka puffin launched the search for microplastics, some of which were so small they had to be detected with ultraviolet light. And detection of microplastics prompted the investigation into the effects of microplastics.

Just as they are indicators of other aspects of ecosystem health, birds would be good indicators of plastics in the environment, Causey and his colleagues figured—and a practical way to start the daunting task of understanding microplastics loads in Alaska waters, where little such work has been done.

"We can't filter the ocean," he said.

The story of plastics in the ocean is not new. The case of the albatrosses on Midway Island in the Pacific Ocean, found dead of starvation but their bodies packed with ingested plastic trash, is well-known. Even in waters off the remote Aleutians, occasional deposits of plastic trash—monofilament lines, pieces of Styrofoam, and other debris—have been documented since the 1970s. Some of it has been traced to Soviet or Japanese fishing vessels. Past research has shown an increase in plastics ingestion by seabirds off Alaska, though the focus was on larger pieces, not microplastics.

Still, plastic loads along the Aleutians have not been noticeably large, Causey said. In their surveys on the Tiglax, crews have seen the occasional nurdle, one of the pellets that manufacturers meld together into plastic products, and occasional items on the beaches, but not much more, he said.

The western and central Aleutians are far from any sizable human populations and any suspected local sources of plastics, Padula said. It is likely that whatever bits of plastic brought there are from elsewhere, broken into small pieces by ocean forces along the way as they travel. They might be so small that, unlike the big pieces ingested by the albatrosses in the tropical Pacific, they pass right through the Aleutian birds' bodies.

"So for us, the question became, what happens in that time when the plastic is inside the bird's stomach," Padula said in her presentation at the marine science symposium.

To measure phthalates exposure, Padula and her colleagues examined muscle tissue from 138 birds of 11 species—red-faced cormorant, tufted puffin, parakeet auklet, common murre, glaucous-winged gull, pelagic cormorant, crested auklet, black-legged kittiwake, horned puffin, pigeon guillemot, and northern fulmar. The birds were taken during field research from 2009 to 2015. Of the 138 birds, 30 had some type of inorganic material in their stomachs at the time they were found.

Padula found no noticeable geographic pattern for phthalate contamination among the Aleutian birds. But she did find an important pattern among species.

Contrary to the situation with persistent organic pollutants and mercury, phthalate levels are not magnified higher in the food web. Instead, the birds that eat lowest on the tropic level—crested auklets—had the highest phthalate levels, she said.

That produced a hypothesis: "These birds, which are plankton eaters, are targeting items that probably are plastic but look a lot like plankton. So they're getting confused by those items," Padula said. Risks appear to be lower for "a bird that's eating a fish that might have eaten some plankton," she said.

Padula and her colleagues are now investigating signs for phthalates in parts of the birds' bodies other than muscle tissue, like feathers. So far, 11 of the birds examined, she said, were females carrying embryonic tissue that tested positive for phthalates. Another discovery, like finding the plastic-containing Amchitka puffin, was almost accidental: Phthalates are in bird eggs.

In 2015, when Padula was on St. Paul Island in the Bering Sea and doing work for the local Aleut tribe, community members gave her a gift of six thick-billed murre eggs. The eggs are part of the traditional Aleut diet.

"I ate those eggs," Padula said. But she saved some portions to test for phthalates—and the tests turned out positive. "I consumed subsistence foods that I later detected phthalates in," she said.

On the other side of Alaska, the Sitka Tribe in the southeastern part of the state plans to test shellfish collected at a popular local beach for plastics contamination.

The tribe, with members who are Tlingit people of southeastern Alaska, already tests local harvests for the algal toxins that cause paralytic shellfish poisoning. As the water warms, harmful algal blooms are proliferating, and the tribe has stepped up its examination of clams.

Now the tribe is planning to add a microplastics search to its toxin screening. The short-term goal is to examine at least 50 blue mussels and 50 butter clams retrieved from a popular local beach, said Naomi Bargmann, an Alaska Department of Fish and Game technician who is taking a leave from her state job to work on the project.

The Sitka group lacks the ultraviolet spectrometer that other researchers have used to search for the smallest microplastics, Bargmann said. But it can make use of high-magnification microscopes and filters, thanks to cooperation from Mount Edgecumbe High School, a boarding school for high-achieving Native students from around Alaska.

"Right now, we're relying on visual identification," Bargmann said. The group does plan to preserve samples to be eventually tested for phthalates, she said.

A $30,000 grant from EPA's environmental justice program is expected to fund the project, though details were still being worked out, Bargmann said.

This article originally appeared on Oceans Deeply, and you can find the original here. For important news about our world’s oceans, you can sign up to the Oceans Deeply email list.